In response to the Search Engine Land piece about Google Ad Strength that I responded to, Google says Ad Strength is not used in the auction.

But!

Ad Strength looks at 4 categories that have been identified to result in better performance through regression analyses.

For example, a low Ad Strength could explain a lack of impressions, but low Ad Strength doesn’t prevent ads from entering into auctions.

It’s a feedback mechanism for creative content and meant to be used as a helpful guide to improve the effectiveness of your ads. Again, it isn’t used directly in the auction.